NATS 1740 Chapter Notes - Chapter 23: Accelerating Expansion Of The Universe, Density

• School: York University
• Department: Natural Science
• Course: NATS 1740
• Professor: Tatiana Paulin

Document Summary

Chapter 23: dark matter, dark energy, and the fate of the universe. Dark matter- matter that we infer to exist from its gravitational effects but from which we have not detected any light. Dark matter dominates the mass if the universe. Dark energy-energy that could be causing the expansion of the universe to accelerate. If a galaxy"s total mass is larger than the mass attributed to stars, then the excess mass is dark matter. Galaxy clusters contain 40x more mass in dark matter than in stars. A recollapsing universe- a model of the universe in which the collective gravity of all it"s matter eventually halts and reverses the expansion causing the galaxies to come crashing back together. A critical universe- model in which the universe expands more and more slowly as time progresses. Coasting universe- model where the universe expands forever with little change in the rate of expansion. Actual mass density is smaller than critical density.